France plunged into an unprecedented diplomatic crisis with the U.S. and Australia on Friday, after it pulled its ambassadors from both countries over a trilateral security deal between the two nations and Britain.

The rare decision, made by French President Emmanuel Macron, came after Australia said it would scrap a $40 billion deal with French company Naval Group to build conventional submarines.

Instead, it would build at least eight nuclear-powered submarines with U.S. and British technology.

The new alliance – called AUKUS – is meant to strengthen security in the Indo-Pacific.

France called it a stab in the back.

The U.S. and Australia said they regretted France’s decision, and would work to resolve differences in the coming days.

Earlier on Friday, Australian Prime Minister Scott Morrison rejected criticism from France that it had not been warned about the new deal, saying he had raised the possibility in talks with Macron.
“These are matters that President Macron and I have discussed on many occasions.”

France so far has made no mention of pulling its ambassador in Britain, but a diplomatic source said France believed Britain joined the deal in an opportunistic manner.

The strained ties among the long-time allies come as the U.S. and other countries seek additional support in Asia and the Pacific, given concern about the rising influence of a more assertive China.